Is the Apple support only for one year or can I extend it

The Apple warranty is one year. You can purchase AppleCare+, which extends it to 2 years, and can be continued on a month-to-month basis after the 2 years has been reached. However, you must purchase AppleCare+ within 60 days of purchasing your phone. Here is more information→Buy AppleCare+

iPhone comes with 90 days of free technical support and one year of hardware warranty against manufacturing defects. When you bought your phone, you had up to 60 days to purchase an AppleCare+ plan, which would have extended technical support to two years. If you did not do that and you have owned your phone longer than 60 days, you cannot extend the manufacturer warranty on your iPhone.

If you are within the first 60 days from date of purchase, see link to purchase an AppleCare+ Plan --> Buy an AppleCare plan - Apple Support